(1) Field of the Invention
This invention relates to a switching device, to connect an in-feeder wire to an out-feeder wire or to connect the in-feeder wire to a wire receiving terminal.
(2) Description of the Prior Art
In a prior art telecommunications network exemplified by U.S. Pat. No. 3,919,495 to Berglund et al, a cable containing a number of wire pairs is fed from a central office to a pair of cross connect cabinets, designated A and B, which are located within a distribution grid. Feeder pairs which appear at both the A and B interface are called common feeder pairs and patch plugs are used in the prior art to restrict the use of any given common feeder pair to either the A or the B interface unit, but not both simultaneously. When a cable pair is connected in series or patched through the A interface to the B interface by means of a patch plug, a distribution wire may only be attached at the B interface.
An advantage of this type of distribution system is that although common feeder pairs are available at either of the A or B interfaces, the central office identity of these pairs is maintained through the interface. This simplifies administrative procedures in assigning subscription service.
A commercially successful interface system must be reliable and compact so as to permit a large number of terminations to be made within the limited space available in a conventional cross connect cabinet. Also, the smallest number of components should be utilized to cross connect feeder pairs, and non-reuseable and loose parts should be eliminated to provide the most economical solution to the interface problem. It is also important to provide a connection procedure which is simple and unambiguous so as to prevent wiring errors when such a system is utilized in the field.
However, the Berglund et al system suffers from a number of defects. This prior art system requires a large number of non-reuseable patch plugs or jumpers which must be stored within the cross connect cabinet or carried to the cross connect cabinet site by the service personnel. The patch plug configuration of Berglund et al is inconvenient to use. This prior art solution requres complex components and specialized tools which must be skillfully used, to achieve a reliable connection. The complexity of these tasks increases the labor cost associated with making a reliable termination.